Issue #2941106 by droplet, idebr: Site email address in the install profile...

Issue #2941106 by droplet, idebr: Site email address in the install profile form is no longer copied to the user email address

core/modules/system/js/system.es6.js

@@ -23,7 +23,10 @@
     attach(context) {
       // List of fields IDs on which to bind the event listener.
       // Create an array of IDs to use with jQuery.
-      Object.keys(drupalSettings.copyFieldValue || {}).forEach(ids.push);
+      Object.keys(drupalSettings.copyFieldValue || {}).forEach((element) => {
+        ids.push(element);
+      });
+
       if (ids.length) {
         // Listen to value:copy events on all dependent fields.
         // We have to use body and not document because of the way jQuery events

core/modules/system/js/system.js

@@ -10,7 +10,10 @@
 
   Drupal.behaviors.copyFieldValue = {
     attach: function attach(context) {
-      Object.keys(drupalSettings.copyFieldValue || {}).forEach(ids.push);
+      Object.keys(drupalSettings.copyFieldValue || {}).forEach(function (element) {
+        ids.push(element);
+      });
+
       if (ids.length) {
         $('body').once('copy-field-values').on('value:copy', this.valueTargetCopyHandler);